The only engine oil in that area is in the oil pan itself . The trans housing and oil pan are a single unit separate from the engine case , they just bolt together . It doesn't appear from your pics that the oil pan is leaking . Also I've never noticed a difference in smells from engine oil and Formula Plus primary oil . Are you using standard H-D fluids ?
Disclaimer : Don't believe anything I say unless you are absolutely sure that I know what I'm talking about .